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Flash video
Flash video is a file format used to deliver video over the Internet using Adobe Flash Player (initially produced by Macromedia) versions 6–10. Until version 9 update 2 of the Flash Player, Flash Video referred to a proprietary file format, having the extension FLV. The most recent public release of Flash Player supports H.264 video and HE-AAC audio. Flash Video content may also be embedded within SWF files. The format has quickly established itself as the format of choice for embedded video on the web. For instance, the standards documentation for BBC Online deprecates the use of other formats previously in use on its sitesFuture Media Standards & Guidelines - AV Addendum v1.5. BBC such as RealVideo or WMV. Flash Video is viewable on most operating systems, via the widely available Adobe Flash Player and web browser plugin, or one of several third-party programs such as MPlayer, VLC media player, QuickTime, or any player which uses DirectShow filters (such as Media Player Classic, Windows Media Player, and Windows Media Center) when the ffdshow filter is installed. Though the container format itself is open, the codecs used with it are patented. Flash Player The Adobe Flash Player is a multimedia and application player originally developed by Macromedia and acquired by Adobe Systems. It plays SWF files which can be created by the Adobe Flash authoring tool, Adobe Flex, or a number of other Adobe Systems and third party tools. It has support for a scripting language called ActionScript, which can be used to display Flash Video from an SWF file. Because the Flash Player runs as a browser plug-in, it is possible to embed Flash Video in web pages and view the video within a web browser. The primary downside of Flash's FLV player is that it is very inefficient compared to a directly embedded video file, dropping frames when running on slow clients that run directly embedded video perfectly. Format details Commonly, Flash Video files contain video bit streams which are a variant of the H.263 video standard, under the name of Sorenson Spark. Flash Player 8 and newer revisions support the playback of On2 TrueMotion VP6 video bit streams. On2 VP6 can provide a higher visual quality than Sorenson Spark, especially when using lower bit rates. On the other hand it is computationally more complex and therefore will not run as well on certain older system configurations. Flash Player 9 Update 3 includes support for H.264 video standard (also known as MPEG-4 part 10, or AVC) which is even more computationally demanding, but offers significantly better quality/bitrate ratio. The Flash Video file format supports two versions of a so called 'screenshare' codec which is an encoding format designed for screencasts. Both these formats are bitmap tile based, can be lossy by reducing color depths and are compressed using zlib. The second version is only playable in Flash Player 8 and newer. Support for encoding Flash Video files is provided by an encoding tool included with Adobe's Macromedia Flash Professional 8 product, On2's Flix encoding tools, Sorenson Squeeze, FFmpeg and other third party tools. Audio in Flash Video files is usually encoded as MP3. However, audio in Flash Video files recorded from the user's microphone use the proprietary Nellymoser codec. FLV files also support uncompressed audio or ADPCM format audio. Recent versions of Flash Player 9 support AAC (HE-AAC/AAC SBR, AAC Main Profile, and AAC-LC)."Flash Video (FLV) Open Source Flash". Since Flash Player 9 Update 3 Flash Video also supports the MPEG-4 international standard. "What just happened to video on the web". Adobe. Specifically, Flash Player will have support for video compressed in H.264 (MPEG-4 Part 10), audio compressed using AAC (MPEG-4 Part 3), the MP4, M4V, M4A, 3GP and MOV multimedia container formats (MPEG-4 Part 14), 3GPP Timed Text specification (MPEG-4 Part 17) which is a standardized subtitle format and partial parsing support for the 'ilst' atom which is the ID3 equivalent iTunes uses to store metadata. A Flash Player 9 update including a new MP4 H.264 component was released on December 3, 2007."Adobe Flash Player 9 Downloads". Adobe (2007-12-03). Retrieved on 2008-01-31. Additional file formats Because of restrictions in the .flv format, Adobe Systems has created new file formats listed below. Flash player does not check the extension of the file, but rather looks inside the file to detect which format it is. Codec support * H.264 * VP6 * MPEG-4 ASP * Sorenson H.263 References External links * Flash Developer Center - Flash Video Articles * Flash Video (FLV) File Format Specification (adobe.com) * Macromedia Flash FLV Video File Format (Library of Congress) * Java Flash Video Library Category:Container formats